1. Field of the Invention
The present invention relates to a liquid crystal display panel having a high contrast, and more particularly, to a liquid crystal display panel in which smectic liquid crystal, such as antiferroelectric liquid crystal, is used.
2. Description of Related Art
A liquid crystal panel in which a first electrode panel and a second electrode panel are overlapped with separation walls interposed therebetween, and liquid crystal is fills in a space between the first and second electrode panels is known. Transparent electrode arrays are formed on both first and second electrode panels in a perpendicular relation with each other so that they form picture elements at their intersections together with the liquid crystal filled in the space. The separation walls are formed on one of the electrode panels in spaces separating each transparent electrode along the transparent array. The separation walls keep a cell gap between the first and second electrode panels constant without intercepting light going through the picture elements.
The separation walls are usually formed on a surface of an orientation layer on one of the electrode panels by a photo-lithography process. That is, a photo-resist material (for example, S1-400-25 made by Shipley Corp.) is coated by a spin coating method to form a photo-resist layer. The photo-resist layer is exposed to light through a photo-mask and then, developed with a development liquid containing an ingredient, such as sodium phosphate Na.sub.n H.sub.3 nPO.sub.4, for about 30 seconds. Thus, parts of photo-resist layer corresponding to openings for picture elements are removed and the parts forming the separation walls are left. After development, the photo-resist layer is washed in pure water, and then baked. The residual sodium phosphate near of the separation walls, however, cannot be completely removed by the washing process. That is, some of the sodium phosphate is left over on the orientation layer near the of separation walls as a thin film residual. Because of the residual sodium phosphate film, the liquid crystal filing the space between the two electrode panels cannot directly contact the orientation layer near of the separation walls. This means that the liquid crystal located near the separation walls cannot be correctly orientated. The incorrectly oriented liquid crystal causes light leakage in a dark phase which results in a low display contrast.